Dal Quor and Xoriat
The nature of the Outer Planes is a subject hotly debated by the sages of Eberron. One school of thought claims that the planes are interwoven aspects of a single greater reality. Every battle on Eberron has its reflection on Shavarath, and even the smallest flame touches Fernia. According to this theory, all living creatures have innate spiritual connections to many of the planes. These threads are what draw the soul to Dal Quor to dream, or to Dolurrh after death.
Some think that two planes in particular touch the minds of mortals. Dal Quor, the region of dreams, supposedly binds itself deeply to the imagination of mortal creatures. Xoriat, the source of madness, also serves as a font for all powerful emotions: Some believe that overwhelming rage, sorrow, and even joy all flow from the boiling well of Xoriat.
If this is true, psionic power is the energy of the planes channeled and focused through the lens of the mortal mind. The psychic surge of the wilder draws on the raw emotions of Xoriat, while the focused abilities of the psion are dreams forced upon reality.
Sarlona: The Kingdom of the Mind
Sarlona is the seat of psionic power in the Eberron Campaign Setting. This is the homeland of the Inspired and the kalashtar, and duergar, dromites, elans, maenads, and half-giants are all said to live on or under Sarlona. The elders of Adar believe that the continent once was tied closely to Dal Quor, and that this explains the plethora of psionic creatures. However, all manifest zones linked to Dal Quor faded when the plane was thrown out of alignment.
Regardless of the reason, Sarlona is home to many psionic creatures, and it is the simplest place to introduce material from the Expanded Psionic Handbook or Complete Psionic. A Dungeon Master who wishes to restrict the role of psionics in her adventures can insist that psionics have some tie to Sarlona; a changeling who wishes to become a telepath may have to find a kalashtar teacher in Adar, just as the Shadow (of pulp fame, not the Dark Six!) had to travel to Tibet to learn to cloud men's minds.
The realms of Sarlona and the powers of its inhabitants will be explored in greater detail in the upcoming sourcebook, Secrets of Sarlona.
Psionics in Khorvaire
If Sarlona has ties to Dal Quor, Khorvaire has a long history with Xoriat. The mind flayers are iconic figures of the realm of madness, and the psionic powers of these aberrations are legendary. The illithids employed psionic tools and weapons in the war against the Empire of Dhakaan, and these treasures could surface in the present day. Both daelkyr and mind flayers enjoy corrupting other creatures, and the fruits of these experiments can be seen in the illithid heritage traits that can appear in almost any creature. Cults of the Dragon Below produce wilders and ardents who draw their power from madness and raw emotion. Manifest zones could affect psionics just as they do magic; as such, a zone linked to Xoriat would be an excellent place to find a caller in darkness, and wilders of the Dragon Below would build their holy sites in these fortresses of terror.
These ties to Xoriat allow psionics to appear in the wilds of Khorvaire … but what about its civilizations? If a DM wants to give psionics a deeper role in his campaign, here are a few paths to explore.
The Lhazaar Principalities. The people of the Lhazaar Principalities cling to many traditions of old Sarlona — traditions long forgotten by the citizens of the Five Nations. Psionics weren't common in Sarlona before the coming of the Inspired, but a few kingdoms explored the psionic arts, and a few of the principalities may have preserved these techniques, albeit hidden from prying eyes. If a DM is using Complete Psionic, the Six Hidden Houses easily could be spread across the inland region of the Lhazaar Principalities.
Quori Inspiration. The Inspired and the kalashtar are gifted psions, and either group could choose to share their techniques with the people of Khorvaire. In the case of the kalashtar, this would likely be a purely benevolent action, combined with teaching the principles of the Path of Light. On the other side of the coin, if the Dreaming Dark begins training psions, it probably has a hidden agenda … for example, creating a cell that will eventually be tricked into serving as host bodies for Quori spirits. The Dreaming Dark can hide its hand easily by using possessed humans, so people won't realize they are being trained by the Inspired. While the kalashtar are likely to focus on powers with peaceful applications, the Dreaming Dark may create more sinister forces — a guild of soulknife assassins, mercenary psychic warriors, or telepathic spies, who might not even realize the role they are playing in the great game of the Quori.
National Security. In a time of war, nations are always searching for new weapons. With the increasing level of commerce between Sarlona and Khorvaire, the leaders of the Five Nations are slowly learning about the potential of psionic powers. Many may ignore these foreign traditions. Aundair places its trust in arcane magic, while Thrane relies on the divine might of the Silver Flame. However, Karrnath and Breland may choose to explore the psionic arts, either to find ways to counter telepathic spies or to create their own psychic operatives. The King's Dark Lanterns of Breland may be training a unit of lurks, while the Karrns are exploring the battlefield potential of kineticists. Of course, what happens if the top psions in the agency turn out to be Quori sleeper agents?
Removing Psionics from Eberron
This article focuses on ways to expand the role of psionics in the Eberron Campaign Setting. However, some Dungeon Masters may prefer to remove these powers entirely, creating a world in which magic is the sole source of supernatural power.
By default, the primary vector for psionics are the kalashtar, Inspired, and land of Sarlona. If a DM wants to ignore psionics, the simplest answer is to strip these elements from the game. It's easy enough to say that the Quori remain trapped in Dal Quor and never touched the minds of mortals; all that remains is for the DM to decide what new force dominates Sarlona. The Lords of Dust could be the masters of Riedra. It might be a kingdom of aberrations, ruled by illithid tyrants and vile aboleths. Or it might be a mundane human nation, maintaining traditions abandoned by the settlers of Khorvaire.
If a DM doesn't want to use psionics, but still enjoys the story of the kalashtar and their struggle against the Dreaming Dark, there are other options. Instead of psychic power, the kalashtar and Inspired could be natural sorcerers, with an innate talent for shaping arcane energy. A DM who takes this approach may wish to create an arcane equivalent of the mind seed power, as this is a critical tool for the Quori agenda; if such a spell exists, it will be a closely guarded treasure of the Dreaming Dark.